This project focuses on the phenomenon of sign-tracking, which involves the tendency of organisms to orient toward, approach, and often contact localizable and reliable signals (CSs) of imminent nonresponse-contingent appetitive reinforcers (USs). Work on auto-shaping and feature-positive vs.-negative discriminations exemplifies the phenomenon, and it is significant that contacts (e.g., key-pecking or lever-gnawing) of the predictive CS continue in those situations despite the unnecessary effort involved and even if such contact responses are actually programmed to prevent or delay US delivery. A negative counterpart of the phenomenon is the tendency of organisms to retreat from signs that US is not coming. We intend mainly to study (a) spatial, temporal, and predictive relations between CS, US and intertrial intervals, (b) specific properties of CS and US (localizability, modality, etc.), (c) the addition of various response-reinforcer contingencies, (d) the tracking of serial CSs, and (e) the acquisition of sign-reinforcer correlations in situations where S is physically prevented from contacting the sign or consuming the reinforcement (a version of latent learning). We will also test our belief that sign-tracking is intimately involved in such phenomena as behavioral contrast and positive conditioned suppression. Another version of S-S learning will be investigated in studies of "animal imagery". In our opinion the above work may well reveal the dominance of cue-reinforcer over response-reinforcer correlations in controlling skeletal behaviors often regarded as mainly conditioned in "operant" fashion. It may also cast considerable doubt on the operant-respondent distinction and support Pavlov's views on stimulus-substitution. In addition to the above research, we intend to continue work on conditioned inhibition, disinhibition, the functions of S- in discrimination learning, stimulus generalization, and selective attention to conventional operant tasks--topics stressed in our labs over the past 10-15 years.